The rotary internal combustion or Wankel engine is being considered for use as a replacement for conventional reciprocating piston type internal combustion engines in automotive and other similar applications.
The advantages of the rotary internal combustion engine includes simplicity and light weight and small size per horsepower output. Basically the engine consists of a triangular shaped rotor which rotates eccentrically within an epitrochoidal chamber. Seals at the tips of the rotor serve to divide the space within the chamber into three working spaces. As the rotor rotates these working spaces also rotate and their volume changes as a function of rotation. This change in volume is used to compress the fuel air mixture which is subsequently burned and exhausted. The expansion of the burning fuel air mixture provides the energy which is developed into power output.
A significant difficulty encountered in the development and use of the rotary internal combustion engine is the difficulty encountered with the rotor tip seals. During operation of the engine these seals contact the chamber wall and have a high velocity relative to the chamber wall. The resulting friction causes the seal and/or the chamber wall to wear rapidly. Difficulty has also been encountered because of the deleterious effect of thermal and mechanical shock encountered during operation, on the seals.
For economic reasons conventional practice has been to make the cavity walls significantly harder than the rotor tip seals. In this way the wear problem is largely confined to the rotor tip seals. If the rotary internal combustion engine is to be a commercial success, the seals and the cavity wall must last for the life of the engine.